Acentric lithium borate crystals, method for making, and applications thereof

Abstract

Acentric, tetragonal lithium borate crystals are disclosed along with a hydrothermal method for forming such crystals. The crystals possess unique optical, non-linear optical, and other photonic properties and may be formed of sufficient size to be useful in a wide variety of photonic devices. In addition, the disclosed crystals are very hard and can be used in specialty grinding applications such as for grinding optical components for deep UV applications.

1. A method for growing a tetrahedral lithium borate crystal comprising:
 reacting B 2 O 3  and LiOH in an aqueous solution at a temperature of from about 350° C. to about 600° C. and at a pressure of from about 5 kpsi to about 45 kpsi, the aqueous solution comprising a hydroxide ion concentration of from about 1×10 −6  to about 5 molar. 
 
   
   
     2. A method for growing a tetrahedral lithium borate crystal comprising:
 reacting an LiBO 2  feedstock powder and LiOH in an aqueous solution at a temperature of from about 350° C. to about 600° C. and at a pressure of from about 5 kpsi to about 45 kpsi, the aqueous solution comprising a hydroxide ion concentration of from about 1×10 −6  to about 1 molar. 
 
   
   
     3. The method set forth in  claim 2  wherein the LiBO 2  feedstock powder comprises tetragonal LiBO 2 . 
   
   
     4. The method set forth in  claim 2  wherein the LiBO 2  feedstock powder comprises orthorhombic LiBO 2 . 
   
   
     5. An acentric, tetragonal lithium borate crystal comprising the formula LiBO 2 , having a dimension of at least 2 mm in at least one direction. 
   
   
     6. The lithium borate crystal set forth in  claim 5  wherein the crystal belongs to the tetragonal I-42d space group. 
   
   
     7. The lithium borate crystal set forth in  claim 6  wherein the crystal belongs to the tetragonal 42m point group. 
   
   
     8. The lithium borate crystal set forth in  claim 5  wherein the crystal exhibits non-linear optical properties.